Title of Paper:A Study on the Zener-Holloman Parameter and Fracture Toughness of an Nb-Particles-Toughened TiAl-Nb Alloy

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Date of Publication:2018-04-01

Journal:METALS

Included Journals:SCIE

Volume:8

Issue:4

ISSN No.:2075-4701

Key Words:TiAl alloy; Zener-Hollomon parameter; Nb particle; fracture toughness

Abstract:Hot compressive deformation behaviors of a powder metallurgy Ti-45Al-5Nb-0.4W/2Nb (at. %) were investigated at strain rates from 0.001 s(-1) to 1 s(-1) and temperatures from 1050 degrees C to 1200 degrees C. The Zener-Hollomon (Z) parameter can affect the hot deformation mechanism significantly. At a high Z condition, Nb particles played an important role in coordinating the deformation. At a low Z condition, deformation of Nb particles accompanied by dynamic recrystallization (DRX) can act as a dominant softening mechanism. The as-forged pancake exhibits a short rod-like particle-toughened equiaxed matrix. For notched three-point bending (3PB) tests, the fracture toughness of an Nb-particles-toughened high-Nb-containing duplex phase-gamma-TiAl alloy was hardly affected by the loading rate, presenting a peak fracture toughness of about 12.9 MPa.m(1/2). The toughness of the present alloy can be improved by ductile Nb particles. A model based on the Griffith-Orowan-Irwin relation was constructed, which is quite accurate to predict the facture toughness of the present specimen using tensile properties.